Which observation most likely indicates that only a chemical change has taken place?(1 point)
States of matter changes.
The shape changes.
The change cannot be reversed.
A reaction occurs.
A reaction occurs.
Use the table of observed changes to answer the question.
Change # Reacts with another substance? Temperature change? Gas, sound, or light produced? New substance formed?
1 yes yes yes yes
2 no yes yes no
3 yes yes yes yes
4 no no no no
Which changes shown in the table are physical changes?
(1 point)
2 and 3
2 and 4
1 and 4
1 and 2
Change #2 is a physical change because there is no new substance formed, only a temperature change and the production of gas, sound, or light. Change #4 is also a physical change because none of the observed changes indicate a chemical reaction. Therefore, the answer is 2 and 4.
Why is it a physical change to freeze water?(1 point)
Only a phase change occurs.
A temperature change occurs.
Heat is released during the process.
The new and original substances are different.
It is a physical change to freeze water because only a phase change occurs. When water freezes, its physical state changes from a liquid to a solid, but no chemical reaction occurs, and thus the original substance remains the same. Additionally, there may be a temperature change, but it is not necessary for a physical change to occur. Therefore, the correct answer is: Only a phase change occurs.
Which option is an example of a chemical change?(1 point)
stretching a rubber band
chopping vegetables
burning wood
folding paper
Burning wood is an example of a chemical change because it involves a chemical reaction where wood is chemically transformed into new substances such as ash, smoke, and gases. The other options do not involve a chemical reaction, but rather physical changes where the original substance remains the same. Therefore, the correct answer is: burning wood.
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Which observation most likely indicates that only a chemical change has taken place?(1 point)
Responses
A-States of matter changes.
B-The change cannot be reversed.
C- Reaction occurs
D-The shape changes.